CAT Hydraulics and Plumbing Systems 3

Question 1

A rectangular pool holds 50,000 gallons and requires a 6-hour turnover rate. What minimum pump flow rate is needed?

Accepted Answer

139 GPM

Answer

83 GPM

Answer

300 GPM

Answer

500 GPM

Question 2

What condition is most likely indicated when a pool pump produces excessive vibration and a rattling or grinding noise from the impeller area?

Accepted Answer

Cavitation caused by insufficient suction pressure

Answer

Normal operation at a high flow rate setting

Answer

Over-pressurization on the discharge side of the pump

Answer

Electrical motor failure due to prolonged overheating

Question 3

If the pressure gauge on the discharge (return) side of the pump reads consistently higher than normal, what is the most likely cause?

Accepted Answer

A restriction or blockage exists in the return lines or the filter is dirty

Answer

The pump impeller is worn and underperforming

Answer

Air is entering the system through a suction-side leak

Answer

The pool water level is lower than the normal operating range

Question 4

A sudden drop in the pump pressure gauge reading typically indicates which of the following conditions?

Accepted Answer

Air entering the suction side or a blockage restricting flow to the pump inlet

Answer

The pump is now operating at its peak efficiency point

Answer

The filter is clean and offering significantly reduced resistance

Answer

The pool water level has risen above the normal operating range

Question 5

Which instrument should a technician use to verify the actual water flow rate through a pool circulation pipe?

Accepted Answer

Flow meter

Answer

Pressure gauge

Answer

Thermometer

Answer

Conductivity meter

Question 6

What is 'water hammer' in a pool plumbing system, and what commonly causes it?

Accepted Answer

A pressure surge or shock wave caused by the rapid change in water velocity when a valve is closed quickly

Answer

A routine sound produced by water entering the filter media during a backwash cycle

Answer

Vibration from the pump motor that transfers through the connected pipes

Answer

Noise produced by thermal expansion and contraction of PVC pipe in direct sunlight

Question 7

What is the correct formula to calculate the volume in gallons of a rectangular swimming pool?

Accepted Answer

Length (ft) × Width (ft) × Average Depth (ft) × 7.5

Answer

Length (ft) × Width (ft) × Depth (ft) × 5.9

Answer

π × Radius² (ft) × Average Depth (ft) × 7.5

Answer

Length (ft) × Width (ft) × Depth (ft) ÷ 7.5